Micro electromechanical (MEMS) linear actuators are well known. One example of a contemporary MEMS linear actuator is the linear comb drive. Linear comb drives are electrostatic actuators that have interlaced rows of electrodes. At least one row of electrodes is formed upon a stationary base and at least one row of electrodes is formed upon a movable stage.
Electrostatic charges formed upon the electrodes generate forces that effect movement of a stage with respect to the base. However, this movement is comparatively short and is generally limited to less than the length of the electrodes. Although such comb drives are suitable for some applications, such as moving very small electronic and/or mechanical structures over very small distances, contemporary comb drives do not provide enough force or movement for some other desired applications.
For example, contemporary comb drives are not suitable for moving lenses or lens assembles over distances sufficient to effect focusing and/or zooming of cameras, such as the cameras commonly found in contemporary cellular telephones. Indeed, contemporary camera phones lack adjustable focus and zoom because the contemporary motors used to provide these features are simply too large for use in cellular telephones.
Thus, although such contemporary linear comb drives have proven generally suitable for their intended purposes, they possess inherent deficiencies that detract from their overall effectiveness and desirability. As such, it is desirable to provide a linear actuator that has sufficient force to more a lens or lens assembly and that is capable of sufficient movement so as to be suitable for focusing and/or zooming the camera of a cellular telephone.